The present invention relates to an endface polishing method for polishing a tip endface of an optical fiber used for optical interconnection and the like.
Up to now, in the case of connecting facing optical fibers to each other, optical interconnection of a pair of optical fibers is performed by an apparatus having a semiconductor laser provided at a tip end side of one optical fiber and irradiating light from the optical fiber and a pair of optical systems for making the light from the semiconductor laser parallel and converging in the other optical fiber.
In such apparatus, the semiconductor laser and the optical systems must be arranged for the pair of optical fibers with high accuracy so that there is a problem that insertion loss and the like become large when the arranged position is inaccurate.
Because of that, a method is proposed, in which a tip end of the optical fiber is polished in a wedge shape without arranging the semiconductor laser at the tip end of the one optical fiber and light similar as the light from the semiconductor laser is irradiated from the tip endface.
Here, the optical fiber having the wedge shape at the tip end will be described. FIG. 6 are a perspective view and a plane view from the endface direction of the optical fiber.
As shown in the figure, an optical fiber 1 has a cladding 2 and a core 3 provided at the center of the optical fiber, and the cladding 2 is formed in wedge shape. Further, the tip endface where the core 3 is provided is formed so as to project in curved shape.
In the case using such the optical fiber 1 having the wedge shape at the tip end, it is needless to perform positioning of arranging the semiconductor laser so that assembling process is simplified.
However, since eccentricity of the core in such the optical fiber must be less than 0.5 xcexcm, accuracy of polishing has been confirmed by detaching the optical fiber from a polishing apparatus after polishing some degree by the polishing apparatus in polishing the tip end of the optical fiber. Because of that, there is a problem that positioning of polishing is difficult even if the optical fiber is polished attaching at the polishing apparatus again and polishing accuracy becomes bad by dispersion of attaching position.
Further there is a problem that yield is bad because a scar generates at the optical fiber or the optical fiber is broken by detaching the optical fiber often.
Furthermore, there is a problem that polishing time and polishing work become long by confirming polishing accuracy repeating attaching and detaching.
A first mode of the invention to solve the above problem is in an endface polishing method polishing a tip end of an optical fiber held by a jig by a polishing member attached at a polishing disk in an apparatus providing the polishing disk supported by a main body of the apparatus and the jig holding the optical fiber, wherein polishing is performed making a boundary line center axis while observing the boundary line of brightness and darkness formed at outer circumference face of the optical fiber by irradiating substantial parallel light from the predetermined direction crossing at the right angle to the axis of the optical fiber.
A second mode of the invention is in an endface polishing method wherein the boundary line is observed at outer circumference crossing at the right angle to irradiation direction of the parallel light of the optical fiber by observing from direction crossing at the right angle to a face including the predetermined direction in the first mode.
A third mode of the invention is in an endface polishing method wherein the boundary line where light is converged at outer circumference face of the opposite side to irradiating direction of the parallel light of the optical fiber permeating the optical fiber is observed by observing from the opposite side to the predetermined direction in the first mode.
A fourth mode of the invention is in an endface polishing method wherein a core of the optical fiber is projected to axis direction and the boundary line is formed at outer circumference of the core by etching the tip end portion of the optical fiber in any mode of the first to third modes.
A fifth mode of the invention is in an endface polishing method wherein the tip end of the optical fiber is polished in wedge shape or convex spherical surface in any mode of the first to fourth modes.
A sixth mode of the invention is in an endface polishing method wherein polishing by the polishing member is a dry polishing without using polishing abrasive liquid in any mode of the first to fifth modes.
A seventh mode of the invention is in an endface polishing method wherein the polishing is performed by a wet polishing and the abrasive liquid of the endface is removed at the observation in any of the first to fifth endface polishing methods.
A eighth mode of the invention is in an endface polishing method wherein removing of the abrasive liquid is performed by air blow in the seventh polishing method.
A ninth mode of the invention is in an endface polishing method wherein an irradiating unit irradiating the substantial parallel light to direction crossing at the right angle to the axis of the optical fiber is moved when the jig holding the optical fiber is moved in the first mode.
In such the invention, the boundary line of brightness and darkness is formed at outer circumference face of the optical fiber by irradiating substantial parallel light, and by polishing making the boundary line the center axis, it is needless to repeat attaching and detaching because of confirmation of polishing state so as to polish with high accuracy.
A tenth mode of the invention is in an endface polishing apparatus comprising a main body provided rotatably and having a polishing disk holding a polishing member, a jig holding an optical fiber and touching the tip end thereof to the polishing member, a supporting mechanism supporting the jig movably to direction of the polishing disk, and an irradiating unit irradiating substantial parallel light to the optical fiber.